In encoding of a moving image, motion prediction is performed. In motion prediction, a frame is partitioned into blocks and images similar to the blocks are acquired from another frame and used as prediction images. The vectors indicating the images similar to the blocks are referred to as motion vectors and the motion vectors of the blocks are predicted based on the motion vectors of the neighboring blocks of the blocks (for example, see NPL 1 and NPL 2). The vector acquired by prediction of a motion vector is referred to as a prediction vector.
International Organization for Standardization (ISO) is standardizing MPEG-3DV, which is a standard for three-dimensional video encoding and encodes a plurality of viewpoint images and depth maps (NPL 3).